Asepsis process and apparatus

ABSTRACT

A PROCESS AND APPARATUS FOR RENDERING ASEPTIC A CONTAMINATED SURFACE OR SURFACES OF AN OBJECT BEING TREATED, BY ESTABLISHING AN ELECTRIC FIELD THROUGH THE OBJECT AND THROUGH A GAS WHICH CONTACTS THE OBJECT, IN A RELATION PRODUCING A GLOW DISCHARGE IN THE GAS, WITH THE CONTAMINATION ON THE OBJECT (FOR EXAPLE BACTERIA, VIRUSES OR OTHER MICROORGANISMS) SERVING AS A SECONDARY ANODE AND/OR A SECONDARY CATHODE TO THE GLOW. BY VIRTUE OF THIS FUNCTIONING OF THE CONTAMINATION ITSELF AS A SECONDARY ELECTRODE TO THE GLOW, THE CONTAMINANTS ARE BOMBARDED BY ELECTRONS AND/OR IONS WHICH IMPACT AGAINST AND THEREBY KILL OR OTHERWISE DISABLE THE CONTAMINANTS. THE IMPEDANCE TO BY-PASSING OF CURRENT PAST THE OBJECT BEING TREATED IS MAINTAINED HIGH ENOUGH TO FORCE THE CONTAMINATION TO SERVE ITS INTENDED FUNCTION AS AN ANODE OR CATHODE TO THE GLOW.   D R A W I N G

Aug- 17, l977l E. J. HELLUND 3,600,126

AsEPsIs PnocEss AND APPARATUS Filed Feb. s, 1968 2 sheets-sheet A POWERSOLJQCE'.

INI/NTOR. E14/L `I2 HELLUAJD Aug. 17, 1911 Filed Feb. 5, 196B E J.HELLUND ASEPSIS PROCESS AND APPARATUS 2 Sheets-Sheet 2 Elaja povvclzSOUQFE Sou POWE? RCF,

INVENTOR.

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?United States Patent O' ce 3,600,126 ASEPSIS PROCESS AND APPARATUS EmilJ. Hellund, 31281 Holly Drive, South Laguna, Calif. 92677Continnation-in-part of abandoned application Ser. No.

533,767, Feb. 21, 1966. This application Feb. 5, 1968,

Ser. No. 702,929

Int. Cl. A611 1/00, 3/00 U.S. Cl. 21-54 25 Claims ABSTRACT OF THEDISCLOSURE A process and apparatus for rendering aseptic a contaminatedsurface or surfaces of an object being treated, by establishing anelectric eld through the object and through Ia gas which contacts theobject, in a relation producing a glow discharge in the gas, with thecontamination on the object (for example bacteria, viruses or othermicroorganisms) serving as a secondary anode and/ or a secondary cathodeto the glow. By virtue of this functioning of the contamination itselfas a secondary electrode to the glow, the contaminants are bombarded byelectrons and/ or ions which impact against and thereby kill orotherwise disable the contaminants. The impedance to 'by-passing ofcurrent past the object being treated is maintained high enough to forcethe contamination to serve its intended function as an anode or cathodeto the glow.

CROSS REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of my copending application Ser. No. 533,767, filedFeb. 21, 1966, entitled Asepsis Process and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to an improvedprocess and apparatus for sterilizing the exposed surfaces of an object,such as for example a lfood product, items used for rst aid, hygienic ormedical purposes, containers, tools, clothing, and the like. The processand apparatus function to very effectively kill, reactivate orchemically alter microorganisms such as bacteria, virus, fungus andmolds, and act to decompose contaminant organic chemical compounds, allin a manner rendering the surfaces of the object being treatedcompletely sterile.

Though various expedients have been proposed and utilized in the pastfor sterilizing objects being treated, all of these prior processes ofwhich I am aware have had certain disadvantages preventing their use inmany of the instances in which sterilization is desired. For instance,it is of course well known that ultraviolet light of certain wavelengths is germicidal, and lamps producing such ultraviolet light havebeen used commercially to kill microorganisms. However, this ultravioletlight does not penetrate well into a shadow zone around an object, andtherefore is not highly effective in killing microorganisms in such ashadow zone. Further, ultraviolet light can be dangerous to persons inthe vicinity, if not controlled and shielded properly.

Similarly, high energy particle bombardment, employing beta, gamma, andX-rays, can also be utilized Ifor the purpose of killing microorganisms,but requires extremely expensive energy generation sources, and is evenmore hazardous to health than are ultraviolet rays, requiring extensivesafety precautions and highly skilled operating personnel.

Another previously utilized and well known -method of sterilizing itemshas been by simply heating them, and thereby raising their temperaturehigh enough to destroy the microorganisms. This type of process has beensatis- 3,600,126 Patented Aug. 17, 1971 factory for many purposes, butin other situations has had various disadvantages, including especiallythe tendency to alter the condition of the item being treated as aresult of the heat developed. In the case of certain food items, forexample, such an elevation of temperature can so drastically change thetaste or condition of the food as to render it completely inedible.

SUMMARY OF THE INVENTION The process and apparatus of the presentinvention are capable of sterilizing initially contaminated surfaces ofa food product or other item or object being treated in a very effectivemanner achieving complete surface sterilization almost instantaneously,and yet overcoming the various disadvantages of the above discussed andother prior processes for this purpose. As will appear, themicroorganisms and other contaminants are killed and deactivated by aprocess which does not substantially alter the condition of the foodproduct or other object being treated, either internally or externally,so that the product remains in substantially its original conditionexcept for the sterilization of its outer surfaces. Also, the processdoes not involve diflicult radiation shielding problems, and can beperformed without any radiation hazard to operating personnel or others.Additionally, I avoid the above discussed shadow problem which isinherent in the use of ultraviolet type radiation.

To achieve these results, I employ a system in which an electric eld isestablished, in a relation such that the field extends through theobject being sterilized, and through a body of gas which contacts asurface or surfaces of the object. The intensity of the electric eld ispredetermined at a value to produce a glow discharge in the gas, withthe conditions being so controlled that the contaminants themselves onthe surface of the object being treated serve as an electrode orelectrodes, that is, an anode and/ or cathode, to the glow. Stateddifferently, the glow is made to attach to the contamination and to thesurface of the object which carries the contamination in a secondaryelectrode relationship. Because the contamination and the sur-face onwhich it is carried are serving as an anode and/or cathode to the glow,the contamination is very effectively bombarded by electrons or ionsmoving rapidly toward the contamination by virtue of its electrodestatus, with resultant collisions of the electrons or ions with thecontaminants in a manner destroying the integrity of the contaminantsand killing or deactivating them. When the contamination functions as ananode, the bombardment of the contaminants is by electrons and often bysome negative ions. When the contamination functions as a cathode, onthe other hand, the bombardment is by positive ions.

In order to assure functioning of the contaminated surface as asecondary electrode to the glow, I maintain sufficiently high impedancealong all possible by-passing paths to prevent electrical conduction ofthe energy along such paths, and thereby lforce devlopment of thedesired anode or cathode relationship between the contaminated surfaceand the glow. For this purpose, I may employ a high impedance `baille orbarrier, or may alternatively utilize an electromagnetic field fordirecting the charged particles along the desired path.

In some instances, the electric field may be set up by a direct currentpower source, preferably producing a pulse of very short duration. Inother situations, I may employ an alternating current power source,acting to repeatedly change the electrode status of a particularcontaminated surface from anode to cathode, back to anode, etc. In thisinstance, the contaminants may be caused to themselves produce the veryelectrons by which they are destroyed, since in their cathode conditionthey produce electrons which tend to move into the glow plasma, andsince the same electrons may subseqeuntly reverse their direction ofmovement and return rapidly toward and bombard the contamination whenthe latter is in its anode condition.

Certain additional advantages can be attained by utilizing alternatingcurrent of a type having an asymmetric wave form, so that the duration,wave shape or amplitude of the electric eld in one direction isdifferent than the corresponding characteristics of the eld in theopposite direction, in a predetermined relationship serving to cause theelectrons and negative ions on one half cycle to bombard thecontaminants in a different manner than do the positive ions on theother half cycle. It will be apparent that many variations of asymmetricwaves maybe employed as may be found desirable for most effectivelykilling or disabling microoragnisrns of different types encountered indifferent sterilizing situations.

BRIEF DESCRIPTION OF THE DRAWING The above and other features andobjects of the invention will be better understood from the followingdetailed description of the typical embodiments illustrated in theaccompanying drawings, in which:

FIG. 1 is a diagrammatic representation of a first form of apparatus tobe utilized for performing a sterilizing process in accordance with theinvention;

FIG. 2 is a transverse section taken on line 2 2 of FIG. 1;

FIG. 3 is a diagrammatic representation of another process embodying theinvention, in this case for sterilizing a bottle;

FIG. 4 shows diagrammatically a system in which the electric eld isgenerated by a changing current in a coaxial coil;

FIG. 5 is an enlarged transverse section taken on line 5--5 of FIG. 4;

FI-G. 5a is an enlarged detail of a portion of FIG. 5;

FIG. 6 is a diagrammatic perspective view of another arrangement forsterilizing an object by a process embodying the invention;

FIG. 7 is a section taken on line 7-7 of FIG. 6;

FIGS. 8 and 9 are views similar to FIG. l, but showing two additionalforms of the invention; and

FIG. shows a typical asymmetric alternating current Wave form which maybe used as the exciting power in my process.

DESCRIPTION lOF THE PREFERRED EMBODIMENTS Referring to FIG. 1 in detail,I show a gaseous glow discharge generating electrical circuit l, havingan electrically insulated, gas tight container 2. Two plate electrodes 3and 5 are connected by electrical leads 4 and 6 respectviely to a powersource 7. A gas atmosphere 8, suitable for the generation of a desirableglow discharge, lls the container 2.

The gas employed within container 2 may be any gas capable of producinga glow discharge when subjected to the electric field resultant from theenergization of plates 3 and S. For best results, it is in mostinstances preferred that the gas be selected from the group consistingof oxygen, nitrogen, carbon dioxide, helium, neon, argon, and mixturesof these gases. The pressure of the gas or gases may be any pressure atwhich the glow discharge can be effectively produced, in most instancesat or below atmospheric pressure, and for best results substantiallysub-atmosphreic (preferably between about 30 mm. and 50 microns ofmercury).

The object to be treated is illustrated at 9 in FIG. l, and ispreferably located between the two plates 3 and 5. This object maytypically be a food product, hygienic or medical article or tool, or anyother item to be sterilized, and may of course assume any of numerousdifferent structural shapes instead of the typically and ratherdiagrammatically illustrated circular shape of FIG. 1. When the object 9is tirst placed in container 2, the upper and lower surfaces 10 and 11of the object are assumed to carry layers of contamination designated 12and 13, containing bacteria, molds, viruses and the like which are to bedestroyed by the treating process. About the object 9, there is provideda batle or barrier 14, which may be formed of glass, an appropriateresinous plastic material, or any other electrically insulative materialcapable of preventing by-passing of electric current vertically pastobject 9. If the object 9 is of the illustrated circular cross section,the baflle or barrier 14 may be annular, to externally and annularlycontact the inner surface of the typically spherical container 2, and tointernally and annularly Contact the peripheral surface 15 of object 9.The container itself may also be formed of, or at least be lined with,an appropriate electrically non-conductive material, such as glass or aresinous plastic material.

The two plates 3 and 5 may be circular about the vertical axis 16 ofFIG. l, and may be formed of an appropriate highly electricallyconductive metal, such as copper. These plates 3 and 5, and the surfaces10 and 11 of object 9, may all be disposed transversely of axis 16, asshown.

Power source 7 may be either a direct current source or an alternatingcurrent source, with the latter being prefered in many instances. Forpurposes of description, assume first of all an installation in whichthe power source is of the direct current type, and functions whenactuated to supply an instantaneous uni-directional pulse orpredetermined potential to plates 3 and 5. This direct current sourcemay be connected to plates 3 and 5 in either direction, that is, so thatelectrode 3 is the cathode and electrode 5 the anode, or vice versa.When, as an example, electrode 3 is operated as a cathode, electronsfrom power source 7 tend to ilow from this cathode 3 downwardly towardanode 5 (usually along with some negative ions), while positivelycharged ions of the gas 8 tend to flow from the anode 5 upwardly towardcathode 3. The voltage employed is so selected, in conjunction with theelectrical characteristics of object 9 and the other parameters of thesystem, as to energize gas 8 to an extent producing a gaseous glowdischarge in the space between electrode 3 and upper surface 10 ofobject 9, and in the space between electrode S and lower surface 11 ofobject 9, with the plasma of this glow discharge including electrons,positive ions and a relatively fewer negative ions. The voltage is notallowed to reach a value high enough to cause arcing between theelectrodes and surfaces 10 and 11.

The conditions are so controlled that the contamination 12 and surface10 at the top of object 9 function as a secondary anode to the glowwhich is above object 9, while contamination 13 is undersurface 11 atthe bottom of the object function as a secondary cathode to the glowwhich is beneath the object. To achieve this result, it is of coursenecessary to provide a high enough voltage between plates 3 and 5 toallow for the potential drops which must necessarily occur at and nearsurfaces 10 and 11 when they serve the desired anode and cathodefunctions. As is well known, in order for the contamination onundersurface 11 to serve as a cathode, there must be a cathode potentialdrop of at least about 300 volts directly adjacent that surface.Similarly, there must be an anode potential drop adjacent upper surface10, though this anode drop is of course small as compared with thecathode drop.

If the dielectric barrier 14 were not provided in FIG. l, the glow andthe electric current conducted thereby could in many instances easilyflow vertically past or by-pass the outer edge of object 9, from theupper side of the object to its underside and vice versa. The barrier14, however, is of such high impedance as to prevent such by-passing ofthe current and glow past object 9, and to thereby force or require thecontamination on the upper and lower surfaces of object 9 to function asanode and cathode respectively to the glow, so that the glow in effectattaches itself directly to the contaminants, with the latterfunctioning as secondary electrodes in the system.

Under these glow discharge conditions, with the contaminants 12 and 13serving as electrodes to the glow, electrons and negative ions fromupper plate 3 move downwardly toward and bombard the contaminants 12 onthe upper surface of object 9, while the positive ions from lower plate5 move upwardly toward and bombard the contaminants 13 on theundersurface of the object. The resultant collisions of electrons andions with the contaminants are of suicient energy to break at least someof the molecular bonds within the organic contaminants, and to therebyvery effectively kill or deactivate those contaminants. I preferablymaintain the glow, and subject the object 9 to this process ofbombardment, for only a very limited period of time, desirably not morethan about one second, and in most instances only a small fraction of asecond. In one installation utilizing direct current in an arrangementsuch as that shown in FIG. 1, the direct current power source 7generated 2000 volts and produced a current flow of l milliamperes persquare decimeter over the cathode 3, with the gas 8 being argon.

In -many situations, the object 9 to be sterilized is essentiallynon-conductive electrically, or very poorly conductive, as for instancein the case of most food products such as meat. In such cases, the glowdischarge will of course be maintained only during build up of theelectrical charges on the upper and lower surfaces of the object 9.However, this very limited almost instantaneous subjection of thecontaminant pathogens to bombardment is sufiicient to destroy them. Whenobject 9 is of an electrically conductive nature, as for instance if theobject is a surgical knife or instrument formed of metal, current mayflow directly through that metal, but the contaminants on the surfacesof the metal will still, under proper voltage and proper guidance, whichmay take the form of magnetic scanning or sweeping, and with an adequatedielectric barrier thereabout, function as an anode and as a cathode,and be bombarded by electrons and ions in the manner discussed.

The advantage of performing the bombardment under glow dischargeconditions resides in the fact that the characteristic energy madeavailable in a glow for a given bond transformation by collision happensto be just the right energy for breaking the types of bonds which occurin biological compounds, that is, the compounds of which the contaminantpathogens are formed, and yet is not great enough to harm the objectbeing sterilized. Specifically, the energy spectrum available for bondtransformation in a glow is .03 ev. to 300 ev. (approximately, for mostgases), which range completely encompasses the spectrum of bond energiesof all biological compounds. This particular energy spectrum is notsupplied in any other type of electrically energized sterilization ortreatment process with which I am familar. For example, in a dielectricheating system, the characteristic energy made available for a givenbond transformation is 0.025 ev. to 0.035 ev., a value far too low toachieve the present purposes effectively. In an ultraviolet system, thecharacteristic energy is approximately 3 ev., and does not coveradequately the range required for proper sterilization. In a Van derGraaff generator arrangement, the characteristic energy made availableis far too great, specifically in the range of 1 mev. to mev., and canbe very detrimental to the object being treated. Thus none of thesesystems can destroy biological bonds with the effectiveness and safetyattainable in a secondary electrode glow discharge bombardment of thetype provided by the present process.

If the connections between power source 7 of FIG. 1 and the two primaryelectrodes 3 and 5 are reversed, the polarities of these plates and ofthe upper and lower contaminant layers are also of course reversed fromthe condition typically illustrated in FIG. 1; but the destructiveaction on the contaminants is essentially the same as discussedhereinabove.

Up to this point in the description of the FIG. 1 arrangement, it hasbeen assumed that power source 7 is a direct current source. In manyinstances, however, it is preferred that source 7 supply alternatingrather than direct current. One advantage of the use of such alternatingcurrent resides in the fact that, when alternating current is used, thepolarities of the electrodes 3 and 5, and therefore the polarities ofcontaminant layers 12 and 13, are reversed repeatedly and regularlythrough many cycles, with the result that the contaminants themselvesare made to produce the very projectiles (electrons) by which they aredestroyed. That is, when one of the contaminant layers 12 or 13 isfunctioning as a cathode, the collisions of positive ions with thecontaminants of that layer cause electron bonds to be broken in thecontaminant pathogens, freeing electrons from those contaminants, whileon the next reversal of potential, when these contaminants commence tofunction as an anode, the same electrons previously freed from them aredriven back against the contaminants to kill them. Further, thetreatment can obviously be continued for a longer period of time in analternating current system than in most direct current systems, since inthe latter a glow can usually be maintained only during the chargingperiod. When alternating current is employed, it may be at virtually anyfrequency at which a glow may be maintained, preferably between about 60cycles per second and 200 megacycles per second, and including audiofrequency, intermediate frequency, and radio frequency ranges, orpossibly microwave frequencies in special situations.

In a gaseous glow discharge as utilized in the present invention, withthe gas desirably being at low sub-atmospheric pressure, the ionizationpotential of the gas may range up to about 24.4 volts (the value forhelium); and in addition a cathode potential fall of about 300 volts ateach cathode (both the primary cathode and the secondary cathode on theobject being treated) is required to maintain the plasma, as well as asmaller anode drop at both the primary and secondary anodes. To supplythese requirements and attain an effective sterlizing action, the powersource, whether A.C. or D.C., should desirably have a value betweenabout 1,000 and 40,000 volts, and preferably between about 1,000 to15,000 volts.

The electron density in the glow is very close to the positive iondensity. At an electron density of 103 lectrons/cc. to 1014electrons/cc. and an electron velocity of 10S-l0g cm./sec. near thecathode, an 8 micron long bacillus, with a 2 micron diameter, isbombarded with 1013 electron impacts per second under averageconditions. In about one second, the impacts deliver about ergs to abacterium. Since the bacterium volume is about 10-11 cc., the one seconddosage is about 1013 ergs per gram of tissue or about 1011 reps, whereone rep denotes an energy absorption of 83 ergs per gram of tissue.

Prior art has established that approximately 105 to 106 rep energyabsorption is lethal to single microorganisms, as well as destroying orgrossly altering many simple organic chemical compounds. (Bellamy, W.D., Goldblith, S. A., Colovos, G. C., and Niven, C. P., Bact. Rev. 266(1955); and also Kertesy, Z. I., Prog. Report, U.S. Army QuartermasterCorps. Con. No. DA 129-Qm 329 (January l-February 29 (1956).) Hence myprocess kills microorganisms or grossly alters organic chemicalstructure in about 10*5 seconds. Therefore, a one millisecond pulse ofmy low pressure glow discharge produces an overkill of undesirablemicroorganisms, Viruses or organic chemicals.

A decided advantage of the present process and apparatus resides in therelatively low power requirements of the system. I typically utilizecurrent densities of only about 2 to 30 ma. per square decimeter ofelectrode. to

generate the gaseous glow discharge at the preferred operating pressurerange of 30 mm. to 50 microns of mercury.

Referring next to FIG. 3, I show a gaseous glow discharge electricalcircuit 20, having a gas tight, electrically insulated container 21lwith a vertically extending wire electrode 22 having a lead wire 23connecting it to a power source 26. A horizontally extending secondelectrode or plate 24 is connected by a second lead wire 25 to theopposite side of the power source 26. A gas atmosphere 27 Capable ofsupporting a glow discharge lls the container 21. A glass bottle 28 mayrest on the horizontal electrode plate 24, with vertical wire 22extending downwardly into the bottle to approximately its lower end,along the vertical central axis of the bottle (which may typically be ofconventional circular cross section). The bottle is filled with the samegas as is container 21, and has its upper end closed by an element 29which is formed of an electricaly non-conductive material such as glass,and serves the function of the dielectric bafiie or barrier 14 of theFIG. l arrangement. Element 29 at its lower end may typically take. theform of a cap adapted to fit over and thus close the upper end of thebottle. The cap or element 29 encircles and insulates the electrode 22as it extends upwardly above thebottle to the top of the container, sothat the electrode 22 is exposed to the gas atmosphere only at alocation within the bottle. The two electrodes 22 and 24 may of coursebe formed of any appropriate electrically conductive material, such ascopper.

To describe the functioning of the apparatus of FIG. 3, assume first ofall that power source 26 is of the direct current variety, operating forexample at 1000 volts, and is so connected as to cause wire 22 tofunction as a cathode while plate 24 serves as an anode. Also, assumethat source 26 supplies a timed pulse of say 0.5 second duration, with acurrent density of, for example, 20 milliamperes per square decimeter ofanode plate area. Such a pulse will ionize helium gas both within andabout the bottle to a glow discharge condition, with any contaminationon the internal surface of bottle 28 serving as an anode to the glowwithin the bottle, while any contamination on the outer surface of thebottle becomes a cathode to the external glow. That is, as in FIG. l,the glow attaches directly to the contamination in secondary electroderelation and kills or deactivates all living microorganisms by thepreviously discussed bombardment with electrons and ions. To assurefunctioning in this manner, the insulative element 29 is given a highenough impedance to by-passing of current between the primary cathode 22and anode 24 to require the discussed establishment of the contaminantsurfaces as secondary electrodes. Element 29 may of course be suitablysealed with respect to the wall of container 20, as at 30, to maintainthe gas tight integrity of the container. The arrangement of FIG. 3 mayof course also be operated in reverse manner or be energized byalternating rather than direct current.

In the variational arrangement of FIGS. 4, 5 and 5a, there is shownanother type of gaseous glow discharge circuit illustrated generally at50, operating in a hermetically sealed typically spherical container 51formed of electrcally insulative material. A helical coil 52 within thecontainer is connected by leads 53 and 54 to an alternating currentpower source typically illustrated as a transformer 55. An atmosphere ofionizable gas or gases, typically air in this instance, is maintainedwithin container 51, preferably at a sub-atmospheric pressure, such asfor example 5 millimeters of mercury. The alternating current suppliedto coil 52 produces an electric field within the coil following acircular path about axis 57 of the coil, with that path beingillustrated at 58 in FIG. 5. The coil is operated at a potential whichwill give the circular' field along path 58 a value sufficient to set upa glow discharge through the gas, with the glow discharge of course alsofollowing the defined circular path (and other similar circular paths).The object or objects to be sterilized are positioned in the path of theelectric field and the glow discharge, two such objects beingillustrated at S9 and 66 in the figures. These objects may be located atopposite sides of axis 57, and each may typically in this particularexample take the form of a hollow rectangular container 61 formed of asuitable resinous plastic material and containing a hot food product 62.As in the other forms of the invention, a dielectric barrier is providedfor preventing by-passing of the glow discharge current about theperipheries of the two objects or packages 59 and 60. This barrier isillustrated as taking the form of a circular disc or plate 63 of glassor other non-conductive material extending diametrically across thesperical container 51 and dividing the interior of the container intotwo compartments 64 and 65 (FIG. 5. Barrier 63 may contain rectangularopenings 66 and 67 dimensioned to exactly receive objects 59 and 60 andcontinuously contact those objects about their peripheries. The barrieralso of course contains openings through which the various turns of thecoil pass. Within the food containers 61, there is provided anatmosphere of gas (typically air) capable of supporting a glowdischarge, and maintained at a pressure at which the discharge can beproduced under the excitation conditions encountered.

When coil 52 is energized, the circular field following path 58, andother similar circular paths about axis 57, acts to produce a glowdischarge within each of the containers 61, as well as at the outside ofthe containers. Whatever contamination is present on the vertical wallsof containers 61, as well as on the vertical surfaces of the food 62itself, serves as an anode or cathode to the glow, in the same mannerthat the contamination on the upper and lower surfaces of the object 9in FIG. 1 functions as an anode or cathode. More specifically, referringto the upper treated object 59 of FIG. 5, as enlarged in FIG. 5a, whenthe alternating current power supply is in a first half of its cycle,the circular electric field within the coil acts to cause thecontamination on the left surface of the left hand wall 166 of the foodcontainer 61 to assume a positive charge, and thereby function as ananode to the glow at the outside of the package, while the right handsurface of this wall 166 assumes a negative charge, and functions as acathode to a glow extending from that surface rightwardly to the lefthand (anode) surface of the food product 62. The right hand surface ofthe food product and the left hand surface of a final container wall 167serve as cathode and anode respectively to a second glow extendingtherebetween, while the right hand surface of wall 167 becomes a cathodeto an external glow extending semi-circularly to the lower package 60.Thus, the impacting of electrons and ions against the contamination onthese various surfaces of the containers 61 and their contentseffectively kills the contaminants on those surfaces. The glasspartition 63 provides a sufiiciently high impedance to by-passing of thecurrent past the periphery of the packages 59 and 60 to require theestablishment of the discussed anode and cathode conditions on thecontainer walls. Also, the food product 62 of each package may typicallycontact the walls of its container 61 continuously about the peripheryof the food product, so that the impedance to by-passing of current pastthe product within the container is high enough to require functioningof the surfaces of the food product itself as electrodes. As will beapparent, when the direction of the alternating current reverses, all ofthe secondary electrode polarities discussed in connection with FIG. 5aalso reverse, to attain the previously discussed advantages of suchalternating polarization (the term secondary electrode being defined inthis application as applying to the arrangement of FIGS. 4, 5 and 5aeven though the system of these figures does not in fact include anyprimary electrodes).

ln a typical arrangement of the type illustrated in FIGS. 4, and 5a,coil 52 may be operated at an audio frequency, say for example 15,000cycles per second, and at a suitable potential for producing andmaintaining the desired glow and secondary electrode conditions,typically for example at a potential gradient of 200 volts percentimeter of glow length. The alternating current power may be appliedfor a suitable relatively short interval, for example 100 milliseconds,predetermined to be short enough, and at a low enough oxygen gaspressure, to assure that the taste of the food will not be alteredsubstantially by oxidation processes.

As a further example, I may employ a coil type circuit generallysimilarto that of FIGS. 4, 5' and 5a, but in which a radio frequencyrather than audio frequency power source and coil are utilized,typically at a frequency in the 1 to 2100 megacycle range. The radiofrequency coil may as an example have a power input of l0 to 2() wattsat a potential gradient of 200 volts/cm. Sterilization of the food insuch an arrangement can be attained in much less than a second, with thepressure of the air in container 51 and within the food packagedesirably being relatively low, as for example about 20 mm. of mercury.The container 61 of the food should be non-metallic, to preventelectromagnetic shielding of the food contained therein. It is also ofcourse possible to use intermediate frequencies as well as the mentionedaudio and radio frequencies.

I-n order to assure sterilization of all of the various externalsurfaces of a particular object being treated, the glow producing eldmay be established within that object in a plurality of differentdirections, either by rotating or otherwise turning the object todifferent positions for successive energization in different directions,or by use of a plurality of different electrodes or coils. FIGS. 6 and 7show diagrammatically such a multiple electrode arrangement in which atypically cubical object 70 is to be sterilized by three different pairsof electrodes, including a rst pair 71 at two opposite sides of theobject and disposed perpendicular to a rst axis 72, a second pair ofelectrodes 73 at two other sides of the object and disposedperpendicular to an axis 74, and a third pair of electrodes 75 at theiinal sides of the object and disposed perpendicular to a third axis 76.As will be apparent, the three axes 72, 74 and 76 of the different pairsof electrodes are mutually perpendicular. All of the electrodes may becarried by an essentially cubical body 77 of electrically non-conductivehigh impedance barrier material serving the function of the dielectricbarrier 14 of FIG. 1 (body 77 being shown in broken rather than fulllines in FIG. 6 for clarity). As seen in the FIG. 7 sectional view(which may be considered as representing the cross section of the unitin each of three mutually perpendicular planes), the dielectric materialof body 77 iills in all possible current by-pass locations, leavingunoccupied thereby only the various gas spaces 78 between the electrodesand the outer surfaces 170 of object 70, so that glow discharges may bedeveloped in these spaces between the electrodes and the contaminants onsurfaces 170, with the contaminants serving as secondary electrodesbetween each pair olf primary electrodes 71, 73l or 75. The glow thusbombards the contaminants on surfaces-170 with electrons and ions andthereby attains the desired sterilization of the object.

'It is contemplated that the three sets of electrodes 71, 73, and 74 maybe energized either successively, to successively sterilize differentsides of the object, or simultaneously to attain the completesterilization result at one time. To simplify and clarify the drawings,the power source or sources are not illustrated in FIGS. 6 and 7, but ofcourse may be either of the direct current or alternating current type,and may be of voltages and frequencies and other characteristicscorresponding to those discussed above in conjunction with the otherforms of the invention. Also, the system of FIGS. `6 and 7 shoulddesirably be mounted in a suitable air tight container, with the gas 1Uwithin the glow discharge areas 78 being at an appropriate pressure forionization.

lFIG. 8 shows another form of the invention which may be identical tothat illustrated in FIG. l except for the substitution of a differentmethod of preventing by-passing of the current about the periphery ofthe object. In FIG. 8, instead of utilizing a dielectric baffle as shownat 14 in F'IG. 1, I provide an electromagnetic coil 80 extending aboutthe treated object 9a, and within the air tight container 2a, andcentered about the axis 16a of the electric field. This coil 80 isenergized by a direct current power source 81 acting to produce amagnetic eld extending axially within the coil, parallel tol axis 16a,which magnetic eld serves to guide the electrons and ions in the sameaxial direction, and prevent them from deflecting laterally from theiraxial course. Thus, the impedance to the electric field along anyby-passing path is increased, so that the electric current is requiredto be maintained within the object, in a vertical direction as seen inFIG. 8, to require the functioning of contaminants on the upper andlower surfaces of object 9a as secondary electrodes to the glow, withthe bombardment result and destruction described in connection with FIG.l and the other forms of the invention. It may be noted that magneticfield guidance or bafing of this type is especially useful insterilizing closed and sealed packages of food or the like, as shown at59 in FIG. 5a, since such guidance may be the only convenient way ofrequiring certain surfaces of the product `within the package tofunction as secondary electrodes.

FIG. 9 shows another formi of the invention in which the impedance toby-passing of the current is increased in another way, specically bycooling the space around the periphery of the object, and at thelocation occupied by dielectric baille 14 of FIG. l. In FIG. 9, anannular body of heat conductive material 83 may be provided instead ofthe baille 14, with cooling coils 84 embedded within this element 83,and conducting a cooling iluid therethrough acting to reduce thetemperature of element 83 to a value well below the temperature of theglow discharge, so that the glow discharge has a very high impedancepath through element 83 and peripherally about the object 9b, and isthereby forced through the object, to cause the development of thedesired secondary electrodes on its upper and lower surfaces.

In any of the different forms of the invention, I may encourage thedischarge of electrons from the secondary electrode surfaces bydirecting ultraviolet light against those surfaces, as by ultravioletsources 85 represented in FIG. 9 directed against the secondaryelectrodes surfaces 10b and 11b and/or the primary electrode surfaces ofelectrodes 3b and 5b. I may also employ dielectric heating inconjunction with the discussed glow discharge sterilization procedure,if in certain instances a rise in temperature of the treated object isdesired, or if the contaminant can be discriminantly heated by the glowand by dielectric heating. The synergism encountered in the use of bothglow and dielectric heating should be particularly noted. The glow willelevate the surface temperature (contaminant). This elevation oftemperature makes the contaminant the more vulnerable to dielectricheating corresponding to the elevation of molecular relaxationfrequencies.

When such dielectric heating is to be utilized, the power source whcihenergizes the primary electrode plates, as for instance source 7 of FIG.l, may be designed to provide two types of power, one of the characterdescribed hereinabove and capable of producing the desired glowdischarge and secondary electrode conditions, while the other is of aproper alternating current frequency, matching the relaxation frequencyof molecular dipole orientation, to attain substantial dielectricheating in the object. For example, the glow discharge power may bealternating current of one frequency, say for example 0.1 megacycle persecond, while the dielectric heating power is of ll another frequency,say for example l() megacycles per second.

As mentioned previously, when the exciting potential in my process isalternating current, this potential may have an asymmetric wave form, inorder to attain an optimum unbalanced relation between the ion andelectron bombardment of the contaminants on a particular stuface. Forexample, the alternating potential may have the asymmetric wave formshown at 90 in FIG. l0, in which the positive potential portion 91 ofthe curve is of very short duration and the negative potential portion92 is of much longer duration, or `vice versa (or may be of a differentamplitude or wave shape), so that the bombardment by electrons may be ofa different duration or character than the bombardment by ions, inwhatever relation is found optimum for a particular sterilizingsituation.

Although I have `shown and described certain specific embodiments of theinvention, it will be understood that numerous modications of theinvention can be made, and are to be considered as part of the inventionso long as they fall within the scope of the appended claims.

I claim:

1. The process of rendering aseptic a surface of an object havingcontamination thereon that comprises establishing an electric fieldthrough a gas to said surface and then from said surface through theobject to a second surface thereof, predetermining the intensity of saidfield at a value to produce a glow discharge in said gas which leads tosaid first mentioned surface and which attaches to said contaminationwith the latter serving as an anode or cathode to the glow, maintainingthe impedance to by-passing of current past said object high enough topreclude by-passing of sair surfaces by said current and thereby torequire said contamination to serve as said anode or cathode to theglow, and thereby disabling said contamination by bombardment withelectrons or ions which impact against it in its function as an anode orcathode.

2. The process as recited in claim 1, in which said gas is maintained ata sub-atmospheric pressure.

3. The process as recited in claim 1, in which said gas is maintained ata pressure between about 30 millimeters and 50 microns of mercury.

4. The process as recited in claim 1, in which said gas is selected fromthe group consisting of oxygen, nitrogen, carbon dioxide, helium, neon,and argon.

5. The process as recited in claim 1, wherein said electric field andsaid glow are produced by a short duration direct current pulse.

6. The process as recited in claim 1, wherein said field is energized byan alternating current acting to alternate the direction of the eldrepeatedly.

7. The process as recited in claim 1, wherein said field is energized byan alternating current of asymmetric wave form acting to alternate thedirection of the field repeatedly and asymmetrically and to provide apredetermined relationship between ion and electron excitation of thebiological bonds of the pathogens.

8. The process as recited in claim 1, in which said impedance ismaintained by providing a high impedance batiie along a possible currentby-pass path.

9. The process as recited in claim 1, in which said impedance ismaintained by providing a magnetic field through said object inessentially the direction of said electric field to prevent saidby-passing of current past the object.

10. The process as recited in claim 1, wherein said electric field ispassed through said object in a plurality of different directions todisable contamination on a plurality of different sides thereof.

11. The process of rendering aseptic two surfaces of an object havingorganic contamination thereon that comprises establishing an electricfield through a gas to a rst of said surfaces. then from said firstsurface through the object to the second surface, and then from saidsecond surface into a gas, predetermining the intensity of said field ata value to produce a glow discharge in the gas adjacent both of saidsurfaces which attaches to said contamination on the two surfaces withsaid contamination serving as a cathode and an anode to the glow,maintaining the impedance to by-passing of current past said object highenough to preclude by-passing of said surfaces by said current andthereby to require said contamination on the two surfaces to serve assaid cathode and anode respectively to the glow, and thereby disablingsaid contamination by bombardment with electrons and ions which impactagainst it in its function as an anode and cathode.

12. The process as recited in claim 11, in which said gas is selectedfrom the group consisting of oxygen, nitrogen, carbon dioxide, helium,neon and argon and is maintained at a sub-atmospheric pressure.

13. The process as recited in claim 12, wherein said field is energizedby an alternating current acting to alternate the direction of the fieldrepeatedly.

14. The process as recited in claim 13, wherein an electric field of thecharacter defined is directed through said object in essentially threemutually perpendicular directions to disable contamination on all sidesthereof.

15. Apparatus for rendering aseptic a surface of an object havingcontamination thereon, comprising means for establishing an electricfield through a gas to said surface and then from said surface throughthe object to a second surface thereof, said field being of an intensityproducing a glow discharge in the gas which leads to said firstmentioned surface and which attaches to said contamination with thelatter serving as an anode or a cathode to the glow, said apparatusincluding means to maintain the impedance to by-passing of current pastsaid object high enough to preclude by-passing of said surfaces by saidcurrent and thereby to require said contamination to serve as said anodeor cathode to the glow, whereby said contamination is disabled bybombardment with electrons or ions which impact against it in itsfunction as an anode or cathode.

16. Apparatus as recited in claim 15, wherein saidimpedance-maintaining-means comprises a high impedance battle positionedto prevent said by-passing flow of current past said object.

17. Apparatus as recited in claim 15, wherein saidimpedance-maintaining-means comprises means for establishing a magneticfield through said object in essentially the direction of said electricfield to resist said bypassing fiow of current `past the object.

18. Apparatus as recited in claim 15, further including means forming achamber containing said gas at a subatmospheric pressure and in contactwith both of said surfaces of the object in glow discharge condition,with said two surfaces serving as anode and cathode respectively to theglow to disable contamination on both surfaces.

19. Apparatus as recited in claim 15, in which said means forestablishing the electric field includes two oppositely charged plates.

20. Apparatus as recited in claim 15, in which said means forestablishing the electric field includes an electromagnetic coilproducing said field.

21. Apparatus as recited in lclaim 15, in which said means forestablishing the electric `field includes an alternating current powersource acting to alternate the direciton of the electric fieldrepeatedly.

22. Apparatus as recited in claim 15, in which said means forestablishing the electric field includes an alternating current powersource of asymmetric wave form acting to alternate the direction of theelectric field repeatedly and asymmetrically.

23. Apparatus as recited in claim 15 further including means forproducing an electric field of the character dened through the object atan angle to the first mentioned field to disable contamination onanother surface or surfaces of the object.

24. Apparatus as recited in claim 15, including means for producingelectric fields of the character defined through said object inessentially three different mutually perpendicular directions, and witha glow discharge produced by each field attached to opposite sides ofthe object as an anode and cathode respectively, to disablecontamination on all sides of the object.

25. Apparatus as recited in claim 15, in which gas is in contact withboth of said surfaces of the object in glow discharge condition, withsaid two surfaces serving as anode and cathode respectively to the glowto disable contamination on both surfaces.

References Cited UNITED STATES PATENTS 2,122,741 7/19'38 Haddad 21-542,132,708 10/1938 Smith 2l-54 14 Alexander et al. 21-54UX RobinsonZ50-49.5 Zoubek Z50-49.5

Parks Z50-49.5 Trump 250-49.5 Frhlich 2S0-49.5X Skala Z50-49.5

Menashi 21-54 Frhlich 250-49.5(62)UX Shepard Z50-49.5(62) MORRIS 0.WOLK, yPrimary Examiner B. S. RICHMAN, Assistant Examiner U.S. C1. X.R.

2l--l02; 204-165, 312; Z50-49.5

